164 Journal of Agricultural Research voi. iv, no. 2 



reproduction of decay similar in appearance to that occurring in the two 

 cases described. The acetic-acid development, however, did not occur 

 except in a slight degree in a few instances, and there is no certainty 

 that in these cases it did not result from contamination. Inoculation 

 experiments made in the field upon living material invariably yielded 

 negative results. Inoculation experiments upon seedlings made in the 

 usual manner also failed to produce damping-off when reasonably good 

 conditions of culture were maintained. It was possible, however, to 

 produce a disease which showed the symptoms of root sickness when 

 the soil was excessively wet and the temperature rather adverse. Nat- 

 urally the fungus was easily isolated from such material. The control 

 plants, however, were sickly or diseased on the roots, and it is highly 

 probable that the results obtained in the inoculation experiments with 

 seedlings are to be attributed to physiological injury, which opened the 

 way for the Rhizopus to grow saprophytically upon the tissue. 



Inquiry into the history of the fields that produced the peculiar rot 

 with which this fungus was associated revealed the fact that at least 

 one of them had been flooded for a time and that the other had been 

 excessively moist for several consecutive days prior to the appearance of 

 the disease. In view of these facts and the results of experimental work, 

 it seems reasonable to conclude that the beets were originally killed or 

 at least materially weakened by adverse physiological conditions and 

 that Rhizopus nigricans followed as a saprophyte or vv^eakling parasite 

 producing a characteristic type of decay. 



ALKALI INJURY TO SUGAR BEETS 



During a field trip in Colorado late in August, 191 2, the writer was 

 called upon to visit a beet field in which a peculiar rot was developing. 

 The beets had made a good growth, and most of them were above the 

 average in size. The foliage was luxuriant, but was characterized by a 

 bluish green color and a brittle texture. Little evidence of disease, 

 aside from the abnormal appearance of the foliage, was evident until 

 the plants were pulled, when it was seen that many beets were decayed 

 at the lower portion of the root. Some agency had killed the taproot, 

 following which a soft rot was destroying the tissue. A majority of the 

 plants in the portions of the field most seriously affected showed a 

 characteristic cracking and corroding of the root, like that shown in 

 Plate XXVI. 



Evidences of alkali could be seen on the surface of the soil here and 

 there, and it seemed probable that the deeper branches of the taproot had 

 been killed by alkaline waters. This probability was increased by the 

 fact of the close proximity to the field of an irrigation reservoir the waters 

 of which were evidently quite alkaline, as could be seen from the crust of 

 salts on the ground at the edge of the lake. As a further test upon this 

 opinion, several beets were taken to the laboratory and attempts were 



